Jawwal System (Linked Lists)

Transcription

1 Islamic University of Gaza Faculty of Engineering Computer Engineering Department Data Structures & Algorithms (ECOM 3312) Objective Assignment 1 Jawwal System (Linked Lists) Learn how to implement the functionality of linked lists. Program Description Guess what? Jawwal has lowered the calling rates for students to (0.12 NIS) for one minute; so this means more saving for you! To keep students happy, accounts are now postpaid. Students start with a balance of 50 NIS, and each time they pay their bill, they get another 50 NIS to use. Additionally, now the system can save unlimited records of outbound calls. Therefore, if a user calls 60 friends during a billing period, all calls will be saved. Of course, once the bill is paid, the call history is reset for the next month. For this program, you will implement a basic simulation of this Jawwal system. Students will make accounts, make calls, pay their bills, and more. You will create one linked-list, which will be used to manage all of the accounts (each node of the linked list will be an object of type Student). For the outbound call history, there is now unlimited call history saved during each bill period. How will you implement this? Each Student object will also have another reference, which will refer to a linked list of Call object. There Call objects are the actual outbound calls that were made. Each call object simply stores the number that was called, the duration, and the address of the next node in the list of calls. Please see the UML diagrams at the end of this write-up for more explanation. You will use File I/O to read commands from a file and then print the output to a file. Example commands are ADDACCOUNT, MAKECALL, PAYBILL, etc. then depending on the command, you will either add a new account, process a phone call, search for a student account, and more. But instead of printing to the console window (screen), you will print to an output file. *Sample input and output files have been provided for you.

2 The commands to be implemented are as follows: 1. ADDACCOUNT This command will be followed by the following information in the input file: a student ID (a non-negative integer), first name, last name, and a String representing the new phone number (ex: ). When you process this command, you should make a new Student object, and then you should scan, from the file, the student ID, the first and last name of the student, and the new phone number. *Note: all new accounts receive a free initial balance of 50 NIS for subscribing to the service. Finally, you must insert this object into the linked-list based on the sorted order of the student ID number. Example: If the following line was in the input file: ADDACCOUNT Mohammed Ahmed This would be the output: Command: ADDACCOUNT Name: Mohammed Ahmed Student ID: Phone Number: Balance: 50NIS 2. MAKECALL This command will be followed by a student ID, a non-negative integer and number of call minutes, a non-negative integer value, and a String representing the number that was called. If the record is found in the JawwalAccounts linkedlist and if that record has enough balance for the desired call minutes, it sould be executed and a message printed to output file (see sample output file). The call rate is fixed at the rate of 0.12 NIS/minute. If the ID of the calling student is not found in the linked list OR if the student does not have enough balance for one minute, an error message should be printed. Additionally, if the student has some balance, but not enough to complete the call, the call should be processed, but the length of the call will be limited based on the balance of the customer. A message should be printed stating that the call was terminated due to insufficient balance. (see sample output file). Each Student object have a reference to a Linked Lists Call objects, Calls. Each Call object will store the information of one call (the number and duration). After a call is successfully made, an Call object should be created and then inserted into the linked-list of Call objects. You should insert into the END of this list. To do this, you

3 can either traverse or you can use a tail reference pointer. Because the Call objects are stored in a linked list, this means you can store an unlimited number of calls in the history. Also, once a student pays his/her bill, the linked-list must be reset (make it empty), so it can start recording the history of calls for the new billing period. (see input/output examples for more details). 3. PAYBILL record is found in the JawwalAccounts linked-list, the bill will be paid, the balance will be reset to 50NIS, and the call history will be reset. If the ID is not found, an error message should be printed instead. (see input/output examples for more details). 4. PAYBILLS This command will have nothing else on the line. ALL accounts that have a balance less than the Call rate (0.12 NIS) will get paid. The balance will be reset to 50NIS, and the call history will be reset. 5. DELETEACCOUNT record is found in JawwalAccounts linked-list, it should be deleted and a message printed to output file. If the ID is not found, as error message should be printed instead. (see sample output file). 6. SEARCH record is found, it is printed to the file. If it is not found, an error message should be printed instead. 7. DISPLAYDETAILS This command will be followed by an integer value, the student ID, and it will display all calls details (called number will duration). If the student ID is not found in the linked list, an error message should be printed instead (see sample output file). 8. QUIT This command will not have any other information after it (in the input file). When you scan this command, the program should print a message to the file and then quit. For this program, you will create five classes: Student.java: this class will be used to create objects of type Student. Each Student object will store all the needed information for one student in a specific account (ID, first name, last name, mobile number, etc.). These Student objects will be added (and deleted) from linked list based on the commands from the input file.

4 Call.java: this call will be used to create objects of type Call. Each Call object will store the information for one call (number and duration). These Call objects will be added to the linked list, Calls. Calls.java: this class is the very basic Linked List, which is used to store nodes of type Call. Each Students object has a reference variable, which refers to an object of type Calls. This is a linked list of Call objects. JawwalAccounts.java: this is the main Linked List class! You will use this class to make one object of type JawwalAccounts. Again, this is the actual linked-list class. This is the class that will have the head and will include all the methods that are used to operate on a linked-list of Student objects. Jawwal.java: this is the class that will contain main method.

5 Implementation: For this program, you will create four classes (UML diagram shown below) and the main: Student.java private int ID; private String firstname; private String lastname; private String phonenumber; private double balance; private Calls calls; private int numcalled; private String[] textednumbers; private int numtexted; private static int numstudents = 0; private Student next; Call.java private String number; private int callduration; private Call next; Call() // one or more constructors This is the class for the nodes of the Calls linked list Each Call object is one node of this list Student() // one or more constructors This is the class for the nodes of the JawwalAccounts linked list Each Student object is one node of this list JawwalAccounts.java Calls.java private Student head; JawwalAccounts() // one or more constructor All necessary methods for linked-list operations This is the main linked list class This linked list will store objects of type Student Each Student object is one node of this list private Call head; private Call tail; Calls() // one or more constructor All necessary methods for linked-list operations This is the 2 nd linked list class This linked list will store objects of type Call